Multilayer disk drive motors having out-of-plane bending

ABSTRACT

Various embodiments concern a gimbaled flexure having a dual stage actuation structure. The flexure comprises a gimbal on which a motor is mounted. The motor comprises a first and second terminals and a plurality of actuator layers formed from a piezoelectric material. The plurality of actuator layers comprise serially stacked first, second, and third actuator layers. The plurality of actuator layers are respectively poled and connected to the first and second terminals such that both of the first and second actuator layers expand while the third actuator layer contracts in response to application of a signal across the first and second terminals. The differential motion of the plurality of layers in the motor cause the motor to curl about the contracting third actuator layer. The curling motion causes a portion of the flexure to preferentially curl.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.15/071,762, filed Mar. 16, 2016, entitled MULTILAYER DISK DRIVE MOTORSHAVING OUT-OF-PLANE BENDING, which is a Continuation of U.S. patentapplication Ser. No. 14/579,063 filed Dec. 22, 2014, entitled MULTILAYERDISK DRIVE MOTORS HAVING OUT-OF-PLANE BENDING, now U.S. Pat. No.9,318,136, granted on Apr. 19, 2016, both of which are incorporatedherein by reference in their entireties and for all purposes.

TECHNICAL FIELD

The present invention relates to disk drives and suspensions for diskdrives. In particular, the invention is a dual stage actuation (DSA)suspension having a multilayered motor.

BACKGROUND

Dual stage actuation (DSA) disk drive head suspensions and disk drivesincorporating DSA suspensions are generally known and commerciallyavailable. For example, DSA suspensions having an actuation structure onthe baseplate or other mounting portion of the suspension, i.e.,proximal to the spring or hinge region of the suspension, are describedin U.S. Patent Publication No. 2010/0067151 to Okawara, U.S. PatentPublication No. 2012/0002329 to Shum, U.S. Patent Publication No.2011/0242708 to Fuchino, and U.S. Pat. No. 5, 714,444 to Imamura. DSAsuspensions having actuation structures located on the loadbeam orgimbal portions of the suspension, i.e., distal to the spring or hingeregion, are also known and disclosed, for example, in U.S. Pat. No.5,657,188 to Jurgenson, U.S. Pat. No. 7,256,968 to Krinke, and U.S.Patent Publication No. 2008/0144225 to Yao. Co-located gimbal-based DSAsuspensions are disclosed U.S. Pat. No. 8,681,456 to Miller, U.S. Pat.No. 8,891,206 to Miller, and U.S. Patent Publication No. 2014/0098440 toMiller. Each of the above-identified patents and patent applications isincorporated herein by reference in its entirety for all purposes.

There remains a continuing need for improved performance of DSAsuspensions.

SUMMARY

Various embodiments concern a gimbaled flexure having a dual stageactuation structure. The flexure comprises a gimbal on which a motor ismounted. The motor comprises a first and second terminals and aplurality of actuator layers formed from a piezoelectric material. Theplurality of actuator layers comprise serially stacked first, second,and third actuator layers. The plurality of actuator layers arerespectively poled and connected to the first and second terminals suchthat both of the first and second actuator layers expand while the thirdactuator layer contracts in response to application of a signal acrossthe first and second terminals. The differential motion of the pluralityof layers in the motor cause the motor to curl about the contractingthird actuator layer. The curling motion causes a portion of the flexureto preferentially curl.

Various embodiments concern a suspension structure comprising a flexurecomprising a gimbal and a motor mounted on the gimbal. The motorcomprises a first and second terminals, a plurality of actuator layers,and a plurality of conductive layers. The plurality of actuator layersare formed from a piezoelectric material. The plurality of actuatorlayers comprise a first actuator layer, a second actuator layer, and athird actuator layer. The plurality of conductive layers comprise afirst conductive layer disposed along a top side of the first actuatorlayer, a second conductive layer between and in contact with the firstactuator layer and the middle actuator layer, a third conductive layerbetween and in contact with the second actuator layer and the thirdactuator layer, and a fourth conductive layer disposed along a bottomside of the third actuator layer. The first and third conductive layersare directly connected to the second terminal and the second and fourthconductive layers are directly connected to the first terminal. Thefirst and second layers are both poled in a first orientation and thethird layer is poled in a second orientation different from the firstorientation. The plurality of actuator layers are respectively poled andconnected to the first and second terminals such that both of the firstand second actuator layers one of expand or contract while the thirdactuator layer the other of expands or contracts in response toapplication of a signal having a first polarity across the first andsecond terminals, and further both of the second and third actuatorlayers one of expand or contract while the first actuator layer theother of expands or contracts in response to application of the signalhaving a second polarity that is different from the first polarityacross the first and second terminals.

Various embodiments concern a suspension structure comprising a flexureand a motor mounted on the flexure. The motor comprises a firstterminal, a second terminal, a first actuator layer, and a secondactuator layer. Each of the first and second actuator layers are formedfrom piezoelectric material. The first and second actuator layerstogether comprise the only piezoelectric material of the motor. Thefirst and second actuator layers are adjacent to one another. The pairof actuator layers are respectively poled and connected to the first andsecond terminals such that the first actuator layer one of expands orcontracts while the second actuator layer the other of expands orcontracts in response to application of a signal having a first polarityacross the first and second terminals. The first and second actuatorlayers can be poled in the same orientation. The motor can comprise afirst conductor layer, a second conductive layer, and a third conductivelayer that are interleaved with the first and second actuator layers.

Further features and modifications of the various embodiments arefurther discussed herein and shown in the drawings. While multipleembodiments are disclosed, still other embodiments of the presentdisclosure will become apparent to those skilled in the art from thefollowing detailed description, which shows and describes illustrativeembodiments of this disclosure. Accordingly, the drawings and detaileddescription are to be regarded as illustrative in nature and notrestrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the loadbeam side of a suspension havinga flexure with a dual stage actuation (DSA) structure.

FIG. 2 is a perspective view of the flexure side (i.e., the sideopposite that shown in FIG. 1) of the distal end of the suspension shownin FIG. 1.

FIG. 3 is a perspective view of the stainless steel side of the distalend of a flexure with parts of the suspension removed from view tohighlight the DSA structure having a motor.

FIG. 4 shows the same view of FIG. 3 but with the motor articulating theDSA structure in a first direction.

FIG. 5 shows the same view of FIGS. 3 and 4 but with the motorarticulating the DSA structure in a second direction.

FIG. 6 is a detailed view of the motor of FIG. 3.

FIG. 7 is a cross sectional view of the motor of FIG. 3.

FIG. 8 shows the same cross sectional view of FIG. 7 but while the motoris activated to generally expand laterally.

FIG. 9 shows the same cross sectional view of FIG. 7 but while the motoris activated to generally contract laterally.

FIG. 10 is a detailed view of a motor.

FIG. 11 is a cross sectional view of the motor of FIG. 10.

While multiple embodiments are disclosed, still other embodiments withinthe scope of the present disclosure will become apparent to thoseskilled in the art from the following detailed description, which showsand describes illustrative embodiments. Accordingly, the drawings anddetailed description are to be regarded as illustrative in nature andnot restrictive.

DESCRIPTION OF THE INVENTION

FIG. 1 is a perspective view of the loadbeam side of a suspension 2having a flexure 4 with a co-located or gimbal-based dual stageactuation (DSA) structure. As shown in FIG. 1, the suspension 2 includesa baseplate 6 as a proximal mounting structure. The suspension 2includes a loadbeam 8 having a rigid or beam region 10 coupled to thebaseplate 6 along a spring or hinge region 12. The loadbeam 8 can beformed from stainless steel. The flexure 4 includes a gimbal 14 at thedistal end of the flexure 4. A DSA structure 16 is located on the gimbal14, adjacent the distal end of the loadbeam 8. Proximal and distal, asused herein, refers to the relative direction along the longitudinalaxis of the suspension 2. For example, the baseplate 6 is proximal ofthe loadbeam 8. An axes key 13 indicates X, Y, and Z axes in FIG. 1 andin subsequent FIGS. The suspension 2 is generally elongated along the Xaxis in distal and proximal directions. The Y axis represents lateralleft and right directions. The suspension 2, including the flexure 4,are generally co-planar with an X-Y plane defined by the X and Y axes.The Z axis represents height as well as bottom and top orientations.

FIG. 2 is a detailed perspective view of the flexure side of the distalend of the suspension 2. FIG. 2 shows the opposite side of thesuspension 2 relative to FIG. 1. A head slider 18 is mounted to a tongue20 of the gimbal 14, on the side of the suspension 2 that is oppositethe loadbeam 8. The slider 18 is mounted to a slider mounting region ofthe tongue 20. The slider mounting is a surface of the tongue 20 towhich the slider 18 (or component to which the slider 18 is attached)can be attached, such as with an adhesive such as epoxy. It will beunderstood that the slider 18 can be attached to a different portion ofthe gimbal 14. FIG. 2 further shows a motor 22 mounted on the gimbal 14.

The flexure 4 is composed of several layers, as is known in the art. Theflexure 4 includes a stainless steel layer 24. The stainless steel layer24 can serve as a structural backbone to the flexure 4. Metals otherthan stainless steel can be used. The stainless steel layer 24 caninclude spring arms 30. The stainless steel layer 24 can further includea tongue 20. The tongue 20 can be supported by the spring arms 30. Forexample, struts formed from the stainless steel layer 24 can bridgebetween the pair of spring arms 30 and the tongue 20 located therebetween.

The flexure 4 includes a trace portion 26. The trace portion 26 can belocated partially on the stainless steel layer 24 and can extend off ofthe stainless steel layer 24 at various locations, such as in a flyinglead segment. The trace portion 26 can comprise a plurality of traces 28insulated by one or more dielectric layers 25. The traces 28 can beformed from copper or another conductive material. The dielectric layers25 can be formed from polyimide or another polymer. The traces 28 canelectrically connect proximally with control circuitry of a disk driveas in known in the art. The traces 28 can electrically connect distallyto various components, such as the motor 22. The slider 18 can beelectrically connected with one or more of the traces 28 fortransmitting read and write signal along the suspension 2.

FIG. 3 is a perspective view of the stainless steel side of the distalend of a flexure 4 with parts of the suspension 2 removed from view tohighlight the DSA structure 16. The DSA structure 16 includes the motor22 mounted to the gimbal 14 of the flexure 4 between the loadbeam 8 (notshown in FIG. 3) and the head slider 18. As described in greater detailbelow, in response to electrical drive signals applied to the motor 22,the motor 22 drives portions of the gimbal 14, including the tongue 20and slider 18, about a generally transverse tracking axis.

The connectors 34 attach the motor 22 to the flexure 4. Specifically,the pair of connectors 34 connect the lateral ends of the motor 22 toterminal pads 32 respectively located on the pair of spring arms 30.Lateral, as used herein, refers to the left and/or right directionsorthogonal to the longitudinal axis of the suspension 2. The terminalpads 32 can be formed from metal (e.g., copper) and are exposed thoughthe dielectric layer 25 of the flexure 4 to provide access forconnectors 34 to make electrical connections with the traces 28. Theconnectors 34 can connect with respective anode and cathode terminals ofthe motor 22. Connectors 34 also mechanically support the motor 22 onthe flexure 4. The connectors 34 can comprise solder, conductive epoxy(e.g., silver filled), or other material for forming an electrodeconnection.

In FIG. 3, the motor 22 is in a neutral, undriven state in which notracking drive signal is applied to the motor 22. It is noted that themotor 22 in FIG. 3 has a planar profile along the X-Y plane (i.e.extending along proximal-distal and lateral axes). While the thicknessof the motor 22 is measured along the Z axis (presenting height), theprofile of the motor 22 is essentially entirely along the X-Y plane whenin the neutral, undriven state. Rotation of the tongue 20 by actuationof the motor 22 rotates the slider mounting, and thereby the slider 18,about a tracking axis, as demonstrated in FIGS. 4 and 5 and furtherdiscussed herein.

FIG. 4 is a perspective view of the flexure 4 when the motor 22 iselectrically activated to expand. In FIG. 4, a first drive signal isapplied across the motor 22 via the traces 28 and connectors 34. Thefirst drive signal (e.g., having a first polarity) causes the shape ofthe motor 22 to change. More specifically, the length of the motor 22generally expands (e.g., along the Y axis). The expansion of the motor22 mechanically causes the tongue 20, and the slider 18 mounted thereon,to deflect in a first direction about an axis of rotation. The axis ofrotation is generally parallel with the Z axis. As shown, the motor 22exhibits some out-of-plane (e.g., X-Y) motion (e.g., along the Z axis)upon the application of the first drive signal. More specifically, themotor 22 curls away from the flexure 4 when the motor 22 expands suchthat the lateral ends of the motor 22 move away from the slider 18 andthe stainless steel layer 24 relative to the middle of the motor 22. Thecurling motion of the motor 22 means that the motor 22 is bending out ofthe X-Y plane and deflects along the Z axis.

FIG. 5 is the same perspective view of the flexure 4 as FIG. 4 exceptthat in FIG. 5 the motor 22 is electrically activated to generallycontract. The contraction is caused by application of a second drivesignal (e.g., having a second polarity opposite the first polarity)across the motor 22 via the traces 28 and connectors 34. The contractionof the motor 22 mechanically causes the tongue 20, and the slider 18mounted thereon, to deflect in a second direction about the axis ofrotation, the second direction opposite the first direction. As shown,the motor 22 exhibits some out-of-plane motion along the Z-axis upon theapplication of the second drive signal. More specifically, the motor 22curls toward the flexure 4 during contraction such that the lateral endsof the motor 22 move toward the slider 18 and the stainless steel layer24 relative to the middle of the motor 22 which moves away the slider 18and the stainless steel layer 24. The curling of the motor 22 causes theflexure 4 to curls in the same manner. This curling of the flexure 4 canbe advantageous because the curling causes more total motion in theflexure 4. Such motion can be converted into rotation of the slider 18,which provides greater total stroke for articulation of the DSAstructure 16. Out-of-plane Z-axis motion (curling) and in plane X or Ymotion (stretching/contracting) of the motor 22 can both be used to movethe flexure 4 and rotate the slider 18. There are various motorconfigurations that can support the curling profiles of FIGS. 4 and 5,as further discussed herein.

FIG. 6 is a detailed perspective view of the motor 22 and FIG. 7 is across-sectional view of the motor 22 which further shows connectors 34and terminal pads 32. The motor 22 generally includes a top side 36, abottom side 38 opposite the top side 36, a front side 42, a back side 44opposite the front side 42, a first end side 46, and a second end side48 opposite the first end side 46. The motor 22 includes a firstterminal 50 and a second terminal 52. The first and second terminals 50,52 can be formed from gold, copper, and/or other highly conductivematerial. The first terminal 50 includes a first end cap 54 whichdefines the first end side 46 of the motor 22. The first terminal 50 canfurther define a majority of the bottom side 38 as shown. The secondterminal 52 includes a second end cap 56 which defines the second endside 48 of the motor 22. The second terminal 52 can include a firstconductive layer 75, as further discussed herein. The first terminal 50can be electrically connected to one side of a circuit of the flexure 4while the second terminal 52 can be connected to the other side of thecircuit, such that an electric potential can be applied across the motor22, causing current to flow through the motor 22. The first terminal 50is labeled as an anode while the second terminal 52 is labeled as acathode for convenience. It will be understand that the first terminal50 and the second terminal 52 can reversibly serve as either anode orcathode.

The motor 22 is comprised of multiple layers. The motor 22 includes apiezoelectric material 58. The piezoelectric material 58 can compriselead titanate or various other materials that exhibit piezoelectricmovement when subjected to an electric potential. The piezoelectricmaterial 58 is divided into a plurality of piezoelectric materiallayers. The plurality of piezoelectric material layers includes a firstactuator layer 71, a second actuator layer 72, and a third actuatorlayer 73. The plurality of piezoelectric layers are in a stacked (e.g.,overlapping) arrangement. For example, the first actuator layer 71 isadjacent to the second actuator layer 72 and the second actuator layer72 is adjacent to the third actuator layer 73. In some embodiments, themotor 22 can be limited to the first, second, and third actuator layers71-73 and may not include any more actuator layers formed frompiezoelectric material 58. Various other embodiments can include morethan three actuator layers, such as four, five, or more actuator layers.

The motor 22 further comprises a plurality of conductive layersinterleaved with the plurality of piezoelectric material layers. Theplurality of conductive layers includes a first conductive layer 75 thatdefines the top side 36 of the motor 22. The plurality of conductivelayers further comprises a second conductive layer 76, a thirdconductive layer 77, and a fourth conductive layer 78. The fourthconductive layer 78 defines the bottom side 38 of the motor 22. The topside of the first conductive layer 75 can be exposed on the top side 36of the motor 22. In the arrangement of FIG. 6, the bottom side of thefirst conductive layer 75 is in contact with the top side of the firstactuator layer 71. The bottom side of the first actuator layer 71 is incontact with the top side of the second conductive layer 76. The bottomside of the second conductive layer 76 is in contact with the top sideof the second actuator layer 72. The bottom side of the second actuatorlayer 72 is in contact with the top side of the third conductive layer77. The bottom side of the third conductive layer 77 is in contact withthe top side of the third actuator layer 73. The bottom side of thethird actuator layer 73 is in contact with the top side of the fourthconductive layer 78. The bottom side of the fourth conductive layer 78can be exposed on the bottom side 38 of the motor 22.

In the embodiment of FIG. 6, the piezoelectric material 58 is continuousbetween the first, second, and third actuator layers 71-73. As shown,the first, second, and third actuator layers 71-73 form a serpentineshape around the second and third conductive layers 76, 77. In variousother embodiments, such layers of the piezoelectric material 58 may notbe in contact with each other and may be separated by one or more layersof non-piezoelectric material. In some embodiments, each of theplurality of actuator layers (e.g., first, second, and third actuatorlayers 71-73) are fabricated separately, including being poled, beforebeing combined into the motor 22 as separate actuator layers. In thisway, each actuator layer may be in contact with one or more otheractuator layers in the motor 22, but the actuator layers may not beformed from a single piece of continuous piezoelectric material 58.

The plurality of conductive layers can be formed from conductive metal,such as gold or copper. The first terminal 50 can comprise the secondand the fourth conductive layers 76, 78 as well as the first end cap 54.More specifically, the second and the fourth conductive layers 76, 78can be connected to, or continuous with, the first end cap 54. The firstand the third conductive layers 75, 77 are not directly connected(mechanically and electrically) to the first terminal 50. The secondterminal 52 can comprise the first and the third conductive layers 75,77 as well as the second end cap 56. While the first and thirdconductive layers 75, 77 are not directly connected to each other, theseelements may be directly electrically connected to each other by theconnector 34, such that a signal applied to the second terminal 52 isequally applied to each of the first and third conductive layers 75, 77.In alternative embodiments, the first and the third conductive layers75, 77 can be directly connected to each other by the second end cap 56extending along the second end side 48, such as by being continuous witheach of the first and the third conductive layers 75, 77, similarly tohow the first end cap 54 is attached to the second and fourth conductivelayers 76, 78. The second and the fourth conductive layers 76, 78 arenot directly connected (mechanically and electrically) to the secondterminal 52. The first terminal 50 is not directly electricallyconnected to the second terminal 52. A differential signal appliedacross the first and second terminals 50, 52 causes current to flowthrough the piezoelectric material 58. The first, second, and thirdactuator layers 71-73 are electrically in parallel between the first andsecond terminals 50, 52 such that, in some configurations, approximatelyequal electric potentials will be developed in the first, second, andthird actuator layers 71-73 and approximately equal levels of currentwill flow through the first, second, and third actuator layers 71-73.The differential signal causes an electric potential to be developedbetween the first conductive layer 75 and the second conductive layer76, thereby causing current to flow between the first conductive layer75 and the second conductive layer 76, through the first actuator layer71 therebetween. The differential signal causes an electric potential tobe developed between the second conductive layer 76 and the thirdconductive layer 77 thereby causing current to flow between the secondconductive layer 76 and the third conductive layer 77, through thesecond actuator layer 72 therebetween. The differential signal causes anelectric potential to be developed between the third conductive layer 77and the fourth conductive layer 78 thereby causing current to flowbetween the third conductive layer 77 and the fourth conductive layer78, through the third actuator layer 73 therebetween. This flow ofcurrent through the piezoelectric material 58 causes the first, second,and third actuator layers 71-73 to expand and contract, as furtherdiscussed herein.

The piezoelectric material 58 does not expand or contract in alldimensions equally upon application of the electrical signal. Rather,each layer of the first, second, and third actuator layers 71-73 has aparticular dipole direction of the crystalline structure, thepolarization of the signal and the dipole direction determining whethereach actuator layer expands or contracts, as further discussed herein.

The piezoelectric material 58 has a crystalline structure which causesthe material to change dimension most dramatically along one directionupon application of a differential signal across the first and secondterminals 50, 52. Each cell of the crystalline structure functions as adipole due to a charge imbalance across the cell. The orientations ofthe dipoles of the cells are generally random in untreated piezoelectricmaterial 58. However, a processing step, called poling, can be performedon the piezoelectric material 58 during fabrication of the motor 22 topole the dipoles in one desired orientation. During poling, untreatedpiezoelectric material 58 is subjected to a strong electric field thatpermanently reorientates most or all dipoles of the cells in a generalor specific direction of the field. The process of poling can beperformed layer-by-layer such that each of the first, second, and thirdactuator layers 71-73 (and other layers as provided) can be poled in aparticular direction which may not be the same direction as the polingdirection of the other layers. The direction along which the dipoles ofa layer generally align is the poling direction. After the process ofpoling is complete, subsequent application of a differential signal(e.g., having a substantially lower strength than the electrical fieldused to pole the layers) causes more of the dipoles to reorientate alongthe poling direction and/or to causes the dipoles to more preciselyalign along the poling direction.

As such, each of the first, second, and third actuator layers 71-73 canhave a similar or different dipole orientation with respect to the otherlayers. The poling direction, and the polarity of the signal across thelayer relative to the poling direction, determines whether the layerexpands or contracts in response to the differential signal. The arrowsof FIG. 7 are used to indicate the relative poling of the first, second,and third actuator layers 71-73. It is noted that the directions of thearrows are used for convenience to distinguish the layers as havingsimilar or different poling directions. The arrows themselves do notnecessarily indicate the direction of dipole orientation. In someembodiments, the actual dipole orientation may extend along thelongitudinal axis of each layer, (i.e. laterally).

As indicated by the arrows, the first and second actuator layers 71, 72are poled in the same direction while the third actuator layer 73 ispoled in a different direction (e.g., opposite the poling direction ofthe first and second actuator layers 71, 72). In this way, the dipoleorientations of the crystalline structure of the first and secondactuator layers 71, 72, are the same, which is in a different directionas the dipole orientation of the crystalline structure of the thirdactuator layer 73.

The relative poling of the first, second, and third actuator layers71-73, and the arrangement of the first, second, third, and fourthconductive layers 75-78 alternatingly connecting to the first and secondterminals 50, 52, causes the motor 22 to curl, as shown in FIG. 8. FIG.8 is the same cross-sectional view as shown in FIG. 7, but duringelectrical activation of the motor 22. The first and second actuatorlayers 71, 72 are adjacent to one another, while the third actuatorlayer 73 is adjacent to the second actuator layer 72 and is poled in adifferent direction than the first and second actuator layers 71, 72.Furthermore, the plurality of conductive layers 75-78 alternate inpolarity such that when a differential signal is applied across themotor 22, each of the first and second actuator layers 71, 72 willexperience the signal at different polarities with respect to theirpoled orientations (even though both of the first and second actuatorlayers 71, 72 are poled in the same direction). The result is that oneof the first and second actuator layers 71, 72 expand while the other ofthe first and second actuator layers 71, 72 will contract in response tothe same signal applied across the motor 22. In the specific example ofFIG. 8, the second actuator layer 72 expands while first actuator layer71 contracts. Because of the reverse poling of the third actuator layer73 with respect to the first and second actuator layers 71, 72, thethird actuator layer 73 expands or contracts together with the secondactuator layer 72, thus doing the opposite (i.e. expanding orcontracting) of the first actuator layer 71. As shown in the example ofFIG. 8, the third actuator layer 73 expands.

The second and third actuator layers 72, 73, will expand or contracttogether while the first actuator layer 71 will the other of expand orcontract in synchrony with the second and third actuator layers 72, 73.More broadly, a pair of adjacent actuator layers will expand or contracttogether while an additional actuator layer, that is adjacent to onelayer of the pair, will the other of expand or contract in oppositesynchrony with the pair of adjacent actuator layers. The pair ofadjacent second and third actuator layers 72, 73 expanding orcontracting together drives the general longitudinal expansion orcontraction of the motor 22, and thereby the deflection of the tongue 20and slider 18. The expansion or contraction of the first actuator layer71, opposite the motion of the pair of adjacent second and thirdactuator layers 72, 73, causes a disparity in motion within the motor22. As shown in FIG. 8, the first actuator layer 71 is contracting whichcauses the expanding second and third actuator layers 72, 73 topartially curl around the first actuator layer 71. The layers of themotor are attached to one another as a whole such that the motor 22curls to accommodate the disparity in motion, thereby causing thecurling motion shown in FIGS. 4 and 8.

FIG. 9 is the same cross-sectional view as FIG. 8 but with thedifferential signal applied to the motor 22 being reversed in polarity.The polarity indicators on the first and second terminals 50, 52 arereversed relative to FIG. 8 to indicate the reversal of signal polarity.As shown in the example of FIG. 9, the first and second actuator layers71, 72 contract laterally (e.g., along the Y-axis) while the thirdactuator layer 73 expands laterally, simultaneously. This disparity inlateral motion causes the expanding first actuator layer 71 to curlaround the contracting second and third actuator layers 72, 73. Thisdisparity in motion causes the motor 22 to curl as shown in FIG. 5.

It is noted that the poling directions of the first, second, and thirdactuator layers 71-73 are examples, and that other poling directions canbe used for the various layers. For example, the poling directions ofthe first, second, and third actuator layers 71-73 can be reversedrelative to what is shown in FIGS. 7-9. Some embodiments may correspondto the dipole orientations shown herein, but the motor 22 may beflipped. Other options are also possible.

In performance testing conducted by the inventors, a three layer motorsimilar to that shown in FIGS. 6-9 exhibited superior stoke performancerelative to a standard five layer motor in which all layers were poledto expand or contract together. More specifically, the three layer motorwas tested to have a 33.5 nanometer/volt stroke while the standard fivelayer motor was tested to have a 13.6 nanometer/volt stroke. Therefore,higher stroke performance can be achieved while using fewer actuatorlayers.

While three layer motors have been demonstrated herein in variousembodiments, it is noted that various other embodiments can include agreater number of layers. Such motors can still exhibit the differentialexpanding/contracting motion as well as a greater number of expanding orcontracting layers (e.g., three expanding layers and one or twocontracting layers, which can be reversed to three contracting layersand one or two expanding layers). Furthermore, such motors can alsoinclude a pair of actuator layers that are adjacent to one another andthat expand or contract together while another actuator layer, adjacentto one layer of the pair of actuator layers, expands while the pair ofactuator layers contracts. For example, a top actuation layer can beadded to the embodiment of FIG. 6 to extend above, and adjacent to, thefirst actuator layer 71 (e.g., in contact with the top side of the firstconductive layer 75) A top conductive layer can then be added along thetop side of the added top actuation layer in a similar manner to thefirst conductive layer 75. The top actuator layer can be poled in thesame direction as the first actuator layer 71 or poled in the oppositedirection. Instead of one top actuator layer being added, two topactuator layers may be added above the first actuator layer 71.Alternatively or additionally, one or two bottom actuator layers may beadded to extend below, and adjacent to, the third actuator layer 73.Similar top and/or bottom actuators layers can be added to the motor 122of FIGS. 10-11. For example, fourth and fifth actuator layers (notillustrated) can be added between the top and bottom conductive layers175, 178, the fourth and fifth actuator layers stacked together with thefirst, second, and third actuator layers 171-173. The fourth and fifthactuator layers can both be above or below the first, second, and thirdactuator layers 171-173, or can be respectively above and below thefirst, second, and third actuator layers 171-173.

FIG. 10 is a detailed perspective view of a motor 122 having analternative configuration. The motor 122 can be mounted on variousflexures, such as that shown in FIGS. 1-5 or any other flexurereferenced herein. The motor 122 can be fabricated and used in anymanner referenced herein except where otherwise noted. FIG. 11 is across-sectional view of the motor 122 of FIG. 10. FIG. 11 further showsconnectors 134 which can be used to electrically and mechanicallyconnect the motor 122 to terminal pads 132 as disclosed herein. Themotor 122 generally includes a top side 136, a bottom side 138 oppositethe top side 136, a front side 142, a back side 144 opposite the frontside 142, a first end side 146, and a second end side 148 opposite thefirst end side 146. The motor 122 includes a first terminal 150 and asecond terminal 152. The first terminal 150 defines the first end side146. The second terminal 152 defines part of the second end side 148.The second terminal 152 is comprised of a top conductive layer 175 and abottom conductive layer 177. The top and bottom conductive layers 175,177 may not contact each other, but as shown in FIG. 11, a connector 134can contact each of the top and bottom conductive layers 175, 177 andelectrically connect the top and bottom conductive layers 175, 177 suchthat they function as though they are directly electrically connected.Therefore, a signal applied to the bottom conductive layer 177 willfreely conduct through the connector 134 to the top conductive layer 175with negligible or no loss.

The first terminal 150 can be electrically connected to one side of acircuit of a flexure while the second terminal 152 can be connected tothe other side of the circuit, such that an electrical potential can beapplied across the motor 122, causing current to flow through the motor122. It will be understood that the first terminal 150 and the secondterminal 152 can reversibly serve and anodes and cathodes.

The motor 122 includes piezoelectric material 158. The piezoelectricmaterial 158 can be similar to any piezoelectric material referencedherein. The piezoelectric material 158 includes only two piezoelectriclayers. The piezoelectric material 158 includes a top actuator layer 171and a bottom actuator layer 172. The motor 122 does not include anyother piezoelectric layers. It is noted that the first and secondactuator layers 171, 172 can be considered first and second actuatorlayers, respectively.

The motor 122 comprises a plurality of conductive layers. The pluralityof conductive layers comprise a top conductive layer 175, a middleconductive layer 176, and a bottom conductive layer 177. The topconductive layer 175, the middle conductive layer 176, and the bottomconductive layer 177 can be considered first, second, and thirdconductive layers, respectively. The top conductive layer 175 definesthe top side 136 of the motor 122. The bottom conductive layer 177defines the bottom side 138 of the motor 122. The middle conductivelayer 176 is sandwiched between the first and second actuator layers171, 172. The top, middle, and bottom conductive layers 175-277 are in astacked and interleaved arrangement with the first and second actuatorlayers 171, 172. A top side of the top conductive layer 175 can beexposed on the top side 136 of the motor 122. The bottom side of the topconductive layer 175 contacts the top side of the top actuator layer171. A bottom side of the top actuator layer 171 contacts a top side ofthe middle conductive layer 176. A bottom side of the middle conductivelayer 176 contacts a top side of the bottom actuator layer 172. A bottomside of the bottom actuator layer 172 contacts a top side of the bottomconductive layer 177. A bottom side of the bottom conductive layer 177can be exposed on the bottom side 138 of the motor 122. The top, middle,and bottom conductive layers 175-277 can be similar to any conductivelayer discussed herein, such as by being formed from a metal such ascopper or gold. The first terminal 150 can be directly connected, orcontinuous, with the middle conductive layer 176.

As shown in FIG. 11, the first and second actuator layers 171, 172 arepoled in the same direction. The piezoelectric material 158 iscontinuous between the first and second actuator layers 171, 172. Asshown, the first and second actuator layers 171, 172 form a U shape andwrap around the middle conductive layers 176. In various otherembodiments, the first and second actuator layers 171, 172 may not be incontact with each other and may be separated by one or more layers ofnon-piezoelectric material.

The arrows of FIG. 11 indicate the relative poling of the first andsecond actuator layers 171, 172 in similar manner to the arrows in FIG.7. The first terminal 150 is not directly electrically connected to thesecond terminal 152. A differential signal applied across the first andsecond terminals 150, 152 causes current to flow through thepiezoelectric material 158. The first and second actuator layers 171,172 are electrically in parallel between the first and second terminals150, 152 such that, in some configurations, approximately equal electricpotentials will be developed in the first and second actuator layers171, 172 and approximately equal levels of current will flow through thefirst and second actuator layers 171, 172. The differential signalcauses an electric potential to be developed between the top conductivelayer 175 and the middle conductive layer 176, thereby causing currentto flow between the top conductive layer 175 and the middle conductivelayer 176, through the top actuator layer 171 therebetween. Thedifferential signal causes an electric potential to be developed betweenthe middle conductive layer 176 and the bottom conductive layer 177thereby causing current to flow between the middle conductive layer 176and the bottom conductive layer 177, through the second actuator layer72 therebetween. This flow of current through the piezoelectric material158 causes the first and second actuator layers 171, 172 to expand andcontract, as further discussed herein.

The poling of the first and second actuator layers 171, 172, and thearrangement of the top, middle, and bottom conductive layers 175-277alternatingly connecting to the first and second terminals 150, 152,causes the motor 122 to curl upon activation. The first and secondactuator layers 171, 172 are adjacent to one another while the top,middle, and bottom conductive layers 175-277 alternate in polarity suchthat when a differential signal is applied across the motor 122, each ofthe first and second actuator layers 171, 172 will experience the signalat different polarities with respect to their poled orientations (eventhough both of the first and second actuator layers 171, 172 are poledin the same direction). The result is that one of the first and secondactuator layers 171, 172 expand while the other of the first and secondactuator layers 171, 172 will contract in response to the same signalapplied across the motor 122. Reversal of the signal polarity willlikewise cause the expansion and contraction movements of the first andsecond actuator layers 171, 172 to reverse. Therefore, the only twoactuator layers of the motor 122 will oppositely expand and contract insynchrony upon electrical activation. The expanding actuator layer willhave a tendency to curl around the contracting actuator layer, asdemonstrated herein in other embodiments.

In an alternative configuration of the embodiment of FIGS. 10 and 11,the middle conductive layer 176 may be removed, the poling direction ofone of the first or second actuator layers 171, 172 may be reversed, andthe first and second actuator layers 171, 172 can be electricallyconnected in series. Such an arrangement is similar to that shown inFIGS. 10 and 11 except that the motor only includes two actuator layersof opposite poling direction that oppositely expand and contract insynchrony upon electrical activation.

Although the present invention has been described with reference topreferred embodiments, those skilled in the art will recognize thatchanges can be made in form and detail without departing from the spiritand scope of the invention. For example, although described inconnection with certain co-located DSA structures, motors and associatedfeatures described herein can be used in connection with other DSAstructures, including other co-located DSA structures and/ornon-co-located DSA structures, such as with baseplate 6 or loadbeam 8mounted motors.

The following is claimed:
 1. A suspension structure, comprising: aflexure, including: first and second spring arms; a tongue having aslider mounting region supported by and located between the spring arms;and a plurality of electrical traces; and a motor, including: at leastfirst and second poled piezoelectric material actuator layers, whereinthe actuator layers are mounted to the flexure; a plurality ofconductive layers on the actuator layers, wherein the conductive layersare electrically connected to the electrical traces; and the poledactuator layers and conductive layers are configured such that theapplication of a first polarity drive signal via the traces causes themotor to curl in a first direction and to rotate the tongue in a firstdirection, and the application of a second polarity drive signal via thetraces causes the motor to curl in a second direction and to rotate thetongue in a second direction.
 2. The suspension structure of claim 1 andincluding connectors to mount the actuator layers to the flexure and toelectrically connect the conductive layers to the electrical traces. 3.The suspension of claim 2 wherein the connectors include conductiveadhesive.
 4. The suspension of claim 2 wherein: the electrical tracesinclude terminal pads; and the conductive connectors connects theactuator layers and conductive layers to the terminal pads.
 5. Thesuspension of claim 4 wherein the connectors include conductiveadhesive.
 6. The suspension of claim 4 wherein: the flexure furtherincludes a pair of struts; and the terminal pads are on the struts. 7.The suspension of claim 1 wherein: the flexure further includes a pairof struts; and the motor is mounted to the struts.